The practice of direct bonding orthodontic appliances such as brackets, tubes and the like to teeth has been long known. There are a number of bonding systems or adhesives on the market for use in direct bonding applications.
It has also been well known to attach appliances to bonding pads by welding or soldering procedures wherein the bonding pads have bonding surfaces of various types to produce the desired bond between the appliances and the teeth. The most well known and widely used bonding pad includes a mesh surface of the type illustrated in U.S. Pat. Nos. 4,068,379 and 4,165,561. It has also been known to provide a bonding surface that is dimpled as in U.S. Pat. No. 4,243,386. Other forms of surface structures have also been known.
Cast appliances having integrally formed bonding pads have also been known. Such integrally formed pads have bonding surfaces formed with holes, cavities and slots such as shown in U.S. Pat. Nos. 4,165,561 (FIGS. 17 and 20); 3,765,091 (FIGS. 1 and 5); and 4,322,206. It has also been known to provide a slotted bonding surface in a cast bracket where the slots on opposite sides of a midline converge toward the midline to define a V-lock configuration. With the advent of a trend toward having more cast brackets, either of metal by investment casting procedures or of plastic by plastic molding procedures, there has been a need to improve the bonding strength of a bracket to a tooth. Other types of metal molding procedures may also be used. While improvements have been made relative to the bonding materials or adhesives, attention has been directed toward improving the bonding strength through the construction of the bonding surface of the appliance.